Variable-volume air-compressor.



M. KURTH. -VARIABLE VOLUME AIR COMPRESSOR.

APPLICATION FILED DEO.11. 1907.

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MAX KURTE, OF FRANKLIN, vPENNSYINJUA, ASSGNOR TO NGERSOLL-BAND GOMIPANVY,

OF NEW YORK, N. Y., A CQRORATIQN 0F NEW JEBSEY, i

lSpeciication ,of Lettere atent.

Patented Qian. l2, 1.909,.

application le eeemner l, 1907. Serial No. Minimi.

.To ali whom it may concern:

Be it known-that I, MAX KURTH, citizen of the United States7 residing at Franklin, in the county of Venango and State of Pennsylvania, have invented certain new and useful Improvements in Variable-Volume Air-Cempressors, of which the following is a specification, reference being had therein to the accompanying drawing.

The oh'ect, construction and operation of my invention are herein fully set'forth, reterence heing had to the accompanying drawings which form a parthereof, and in which:

Figure l represents a fluid compressor cylinder and its adjacent parts, partly in side elevation and partly in section, embodying my invention. Fig. 2 represents the iluid compressor cylinder and its adjacent parta,

partly in top plan and partly in longitudinal central section Fig. B is a transverse scction taken in the lane of the line A A of Fig. l, looking in t e direction of the arrows,

sideralg'ly in some classes of service.

and Fig. 4 is a transverse section taken in the plane of the line B-B of Fig. 1, looking in the direction of the arrows.

The same reference letters indicate identical parts 'in the several views.

To those familiar with the operation of air compressors and the character of service in which they are employed, it is a well known fact that it is -Y necessary to employ some means wherehytiie delivery or output of the compressor'may he automatically regulated in accordance with the amount of compressed Yair l; eing used, and which amount varies conllt is also a well known fact that, in nearly all classes ol compressed air service, compressed air is delivered ly the compressor to a receivcnwhicli is practically a storage reservoir from which the air is drawn tor application and service. lt is hy the pressure oi air in said reservoir that nearly or. quite all ci the devices which 'regulate the volume ci delivery ci the -compressor are actuated. By iai the larger numberoi such devices at present employed are oi the type known as unloaders,"7 the function ol which is when the pressure in the receiver rises to a pre-determined maximum point, to hold either an inlet or a discharge valve open so that ingress and egress of air to and troni the cylinders will talie place through the same valve, hy which. operation no additional air is delivered 'to the receiver during unloaded period,

which continues until the pressure in the receiver falls 1celow said maximum point by reason oi the withdrawal of air therefrom. The application of an unloader to van air compressor, however, does not bring it within the class known as variahle volume comressors, for trie reason that when the unoader is dormant the entire product of the compressor is being delivered to the receiver, and when the unloader is acting no air whatever is being delivered to the receiver; on the 'other hand, a variable volume compressor is one adapted to deliver to the receiver not only the full volume of its produce but any percentage thereof according to the require'- nients ofthe service.

It is the object of my invention to provide a deviceJ by the application oi which to any air compressor, the same may he converted into a variable volume compressor. ln general terms ll accomplish said object by attaching to the cylinder of the compressor a clearance chest provided with a plurality of charnhers, one or more of which chambers may he .automatically placed in communication with the clearance s ace'in the cylinders, thus increasing the vo urne of said ls ace, and correspondingly decreasing the el iciency or relative output of the compressor.

lin the drawingsjl have shown the application of my device to a double actingcompressor, and the following description relates to such application, hut those skilled in the art to which my invention appertains will readily understand that it is equally applicable toa single acting compressor.

The construction oi my device is substantially as follows: l provide a clearance chest l which contains a'plurality ci chambers 2, .3, and 2 3', and at each end .of said chest 1 l lform a' cylinder 'el and Ll each closed at either end and having a piston 5 and 5" operable therein; said cylinders are in longitudinal alinement and their resnective pistons 5, 5

connected together hy means of the liston rod 5, which passes through st 'Dg bones 7, 7 the respective heads oi thecylinders; om said lcylinders ports 2?, 3P and QP, SP lead to the respective chambers oi' the clearance chest; the interior .ofeach of said cylinders fl, if is placed in communication with the clearance space 8,18 in the respective 'end ofr the air compressor cylinder inner end ol cylinders, and

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port' 10 being at the outer end of cylinder 4';

.ports 10 and 10 are normally covered by the pistons 5 and 5 respectively.

' For the purpose of retaining pistons 5 and 5' in the. normal position shown in Fig. 1,"I

emr ay a bell crank 11, one arm of Which en` gages the piston rod 6 and to the .other a'rm of which is attached a lever 12,' upon which is adjustably mounted a vcounterweight 13; approximate to -the fulcrum of said bell crankfll is located a cylinder 14,' having therein a piston 1'5, and into the rear of cylinder 14 is introduced a vipe 16 which leads to the receiver into which) air is delivered by ythe compressor; a connecting rod 17 connects piston 15 with bellcrank 11 in such a manner that the action of said Weight and the action of said piston when actuated bythe re. ceiver pressure, are opposed to one another.

'The operation of my device is substantially as follows: When'the'pressure in the receiver has reached a point sufficiently high that its action u on plston 15 will overcome the action of t e counterweight 1'3-' said point-of pressure being determined by the position of said counterweight upon level" 12-weiffht 13'Will be caused to rise and the action 0I the bell crank Will carry rod 6 and the thereto attached pistons, in the direction indicated by the arrow, vand ports 10 and 10 Will `be uncovered, thus placing chambers 3 and 2 in communication With the clearance space inthe respective end'sy of the air compressor cylinder; this acti 0 n' causes a portion of the compressed `charge mf the compressor cyllnder to enter its respective clearance chamber, and when the piston starts upon `its intake stroke, the coinpressed air in said chamber will be exhausted therefrom, or in other Words, the pressure in` said chamber must first fall to the normal atmospheric pressure, before free or atmospheric air Will be taken into the compressor through the inlet valve, hence the actual discharge from the compressor into the receiver.'

will be relative t-o the amount of air entering thel clearance chestduring the compression stroke and 'returning therefrom during the suction stroke. If, under this condition, the

pressure in the receivercontinues to rise,- urther action thereon upon plston 15 will cause, as aforesaid, a further action of the bell crank and a corresponding movement of pistons 5 and 5', andports 2p and 3P will be uncovered this adding the additional volumeA of chambers 2 and 3 to the clearance space,

which will cause a corresponding reductionl `'of the output of compressed ai;` from the compressor.

A` is a by-'pass byv means of which pressure lis established uponboth sides of the pistons 5 5 to balance thev same.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A In a variable volume 'Huid compressor, the combination Witn the tluid compressor cylinder and thereceiver yfor the compressedfluid. generated by said compressor, of a clearance chest having-.therein a plurality of compartments and 'means for successively placing the compartments in 'communication With 'the clearance space in Saidicylinder'as the pressure in the receiver rises to diilerent predetermined points.

2. In a variable volurn'e'iiuid the combination With 'the yfluid compressor cylinder and the receiver lor thek compressed Ltluid generatedby said compressor, ofga clearance chest having therein a pluralityf'ofcompartments and means for successively, (plac-- ing the compartments fin communication with the` clearance space 1n said ,cylinder as the 'pressure in the receiver rises to different r compartments and automatic means for successively placing the compartments communication With the clearance `space in said cylinder as the dpressure inthe receiver rises to dierent pre etermined.points 4. In a variable volume fluid compressor, the combination with vthe fluid compressor cylinder andthe receiver for the compressed fluid generated by said compressor, of a clearva'ncec'hest having therein a plurality Ofcompartments and automatic means for successively placing the compartments in communi-v cation with the clearance space in said cylinder as the pressure in the'receiverv rises to different predetermined points 'and to successively close communication between the said compartmentsand clearancel space in said cylinder as the pressure in the receiver falls to diiierent predetermined points.

5. In a variable volume fluid compressor,v the combination withthe fluid compressor cylinder and the receiver forl the compressedA fluid generated by said compressor, of a clear-y ance chest having therein a'plurality of ycompartments and fluid pressure controlled means for successively placing thecompartments in communication Withthe clearance space in said cylinder as the pressure inthe receiver rises `to vdierent .predetermined points.

6. Ina variable volume uid compressor,

cylinder and the receiver for4 the compressed tluid generated' bysaid compressor, of a c-learance chest having therein a plurality ,of compartments, 'and Huid. pressurev 'controlled the combination with the fluid compressor sure in the receiver falls to different predetermined points.

7. In a variable volume fluid compressor, the combination with the fluid compressor cylinder and the receiver for-the compressed fuid generated by said compressor, of a clearance chest having therein aplurality of,coni-' partments and-automatic means for placing one of said compartments in communication with the clearance space in said cylinder when the pressure in said receiver reaches a predetermined point and for successively placing the remainder of said compartments in communication with said clearance space when the pressure in said receiver continues torise.

8. In a variable volume fluid compressor,

the Acombination with the fluid compressor cylinder andthe receiver for the compressed iuid generated by said compressor, of a clearance chest having therein ajplurality of compartments and automatic means for placing one of said compartments in communication with the clearance space 1n said cylinder when the pressure in said receiver reaches a predetermined point and for successively placing thel remainder of said compartments in communication with said clearance space whentlie pressure in said receiver continues to rise and for successively closing communication between said compartments and clearance space in said cylixder as the pressure in the receiver falls. i

l testimony whereof l afliX my signature in presence of two Witnesses.

MAX KURTH Witnesses:

E. R. lNMAN,A y GiLsoN SHAFFER. 

